The government had previously estimated that outflows would hit $455 billion. Way off.

China has been trying to stabilize an economy that has been (seemingly) under siege since the beginning of the year. The stock market has been a whipsaw, falling precipitously on several occasions. And China's currency, the yuan, has been volatile as well.

Government officials have acknowledged that there will be slower growth during China's transition from an investment-based economy to one based on domestic consumption. They've also said they will start enacting reforms to deal with huge problems like debt and overcapacity in the country's corporate sector.

But capital leaving the country at a rate of $1 trillion a year is an even more immediate threat than that, and the problems that caused it — a depreciating currency, for one — have not gone away.

So, in an effort to stabilize the yuan, the government has warned yuan short sellers— even the legendary (but retired) hedge fund manager George Soros — to quit it.

Keeping the yuan from depreciating too fast cost the government $108 billion in December. The more short sellers try to push it in another direction, the more money the government has to expend.